Protected batteries vs IMR - safety

Discussion in 'Battery Issues' started by SteelJan, Jan 4, 2012.

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  1. SteelJan

    SteelJan Super Member Verified Member ECF Veteran

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    Evening all. Say, I see so many folks now going to the IMR batteries because they deliver a high amount of instantaneous current, and it just worries me a bit.

    If a mod or atty/cartomizer ever shorts out while using an IMR battery, there is no protection, the battery will self destruct. Lighthound.com wrote me in answers to several of my questions, "A dead short with an IMR cell will release a tremendous amount of current + heat."

    For many of us who have been vaping with protected lithium-ion batteries all along, we're used to knowing that a dead short in our mod/switch/atty/carto/etc simply means nothing happens. We can fix the problem with the mod, and voila, the batteries aren't even destroyed from the short.

    I'm thinking that at minimum, shouldn't be be letting one another know about the extra care needed to ensure there is no short in a mod set-up before putting in an IMR battery and pressing that button?

    Dunno, is anyone else concerned? Maybe this is being discussed elsewhere already?
     
  2. 440BB

    440BB Vaping Master Verified Member ECF Veteran

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    Thanks for bringing this up! I was under the impression that IMR batteries were implicitly safer than regular lithium ion and therefore didn't require protection. I guess I haven't seen it discussed thoroughly on ECF but I might have missed a thread. Based on your post it suggests they are not as safe as protected batteries - is that correct? Experienced advice is greatly appreciated!
     
  3. SteelJan

    SteelJan Super Member Verified Member ECF Veteran

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    An IMR battery does indeed use safer chemistry in that nothing should happen if undervolted during discharge, or overvolted during charge. If it is overvolted or run down too far, it simply dies, it won't work anymore, can't charge it anymore, it's gone. But if it gets a dead short, it's going to violently self-destruct.

    Lithium Ion batteries have a more volatile chemistry, they will violently destruct if overvolted or overvolted. That's why we all agree on using lithium ion batteries ONLY if they have the protection circuitry, a protected lithium ion battery. This tiny protection circuit board prevents the battery not only from being undervolted or overvolted, but also from a dead short; you'll push the vape button and nothing happens, nada, zip.

    Everyone takes our own risks with the big batteries we vape. But at least we ought to know what those risks are, yeah?
     
  4. Ande

    Ande Super Member ECF Veteran

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    I think that it depends on what you're planning to do to them. :)

    Seriously- Because of their much higher C rating, IMR batteries are safer in a lot of scenarios. You can't draw too many amps very easily at all. This is the reason a lot of authorities consider them safer- a lot less likely to melt down.

    In a dead short, though, higher C rating means more current to deliver, in a shorter space of time. On the other hand, protected Li-Ion...well- the protection circuitry is small, not too sophisticated, easily dropped. It can, and sometimes does, fail. If you're using protected Li-ion batts, you need to think of them as "usually protected" rather than "protected." THen you'll be fine.


    Also, if you're not used to using unprotected batteries, you need to be careful (check voltages) to be sure that you aren't overcharging or overdischarging. You can damage them, which certainly shortens battery life and may be dangerous.

    Personally, I'd say that IMR probably are safer for vaping applications, BUT all high power batteries are potentially unsafe. Both protected Li-ion or IMR are safe enough for me, provided that you are careful and reasonably cautious.

    Best,
    Ande
     
  5. SteelJan

    SteelJan Super Member Verified Member ECF Veteran

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  6. 440BB

    440BB Vaping Master Verified Member ECF Veteran

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    So if I understand it a dead short could happen for example if I were to insert a screwdriver into a battery connector while firing. Does it happen in a moment or does it require this to be for a length of time? Sorry I have limited understanding of this stuff, but I want to assess the risk. Is there a most likely scenario for this to happen on an ecig?
     
  7. SteelJan

    SteelJan Super Member Verified Member ECF Veteran

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    Something that happened to me that would have been catastrophic if I'd had an IMR battery in it. But I had a protected lithium-ion battery in it.

    I got a mod from one of the popular modders. It occasionally didn't fire, I'd press the button and nothing would happen. Finally, I took it apart and found there were two wires that the modder had skinned-back too far, occasionally touching, making a short circuit. I rewired the whole thing and all was well. If I'd had an IMR battery in there, with the drip tip in my mouth when the first short happened, well, howdy-bingo.

    I don't know how long it takes for a shorted IMR battery to self-destruct when shorted.
     
  8. zoiDman

    zoiDman My -0^10 = Nothing at All ECF Veteran

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  9. Papa Lazarou

    Papa Lazarou Ultra Member ECF Veteran

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    Interesting video of a deliberate shorting of an AW IMR battery and a Panasonic high output li-ion:



    I''ve had a short of an unprotected IMR in a mod. In my case all that happened was the spring on the negative terminal heated rapidly and collapsed, breaking the circuit. No harm done (apart from a toasted spring!), and the battery was OK. In mods where there is no obvious "fuse" to fail, like a spring or something the battery will presumably heat up a lot more and that could be dangerous.
     
  10. WillyB

    WillyB Vaping Master ECF Veteran

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    Interesting how the T-Shirt printer now turned battery seller refers to the Panasonic as an IMR, which Panasonic does not make. These are the kind of disingenuous vendors who should be avoided.

    Kudos to you Papa for noting that it is in fact a Li-Ion (LiCO) cell.

    Back to the OP most large cells contain protection, in the top. The PTC, a current limiting Positive Temperature Coefficient device installed in the cell cap to limit external currents in the event of an external short to the cell.

    The video shows the PTC in action, but I guess it also shows what the OP is concerned about as the higher density AW true IMR did in fact seem like it could be more dangerous under those extreme conditions.
     
  11. Switched

    Switched ECF Guru ECF Veteran

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    Jan,

    You are right to be concerned. IMO caution goes a long way.

    Although IMRs are not protected they are safer chemistry in which the batt will vent without flame - most important criteria with regards to rechargeable batteries.

    Should a protection circuit fail on a LI Ion batt, it will vent with flame.

    Someone had a eGo 900 or 1000mAh go nuclear on them.

    Folks need to educate themselves wrt batteries and a good place to start is Welcome to Battery University or the layman's version Vape Central: Battery - FAQ

    I think the best point to remember is that should a battery start getting hot, break the circuit (disconnect atty or end cap) thermal runaways can be prevented when they start, if one is aware of the situation.

    Thanks for posting :) and raising awareness
     
  12. Shilo

    Shilo Vaping Master Verified Member ECF Veteran

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    I think there is a difference between the AW IMR and the High Drain but I could be wrong. Before I bought any batteries I read all the guidelines for safety on the thread mentioned above. I think there is an inherent small risk with any battery usage. I am glad you are OK Jan and sorry to hear about your trouble with your mod.
     
  13. Eliteedge_7

    Eliteedge_7 Senior Member ECF Veteran

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    thanks for bringing this up.
     
  14. SteelJan

    SteelJan Super Member Verified Member ECF Veteran

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    High-drain and IMR's are the same thing. Oh, no, I didn't fret over this mod, I have bunches, have made quite a few and have created designs for other modders. I'd gotten this one to demo it in one of my video reviews, to throw some support to the modder. But thanks a bunch!
     
  15. SteelJan

    SteelJan Super Member Verified Member ECF Veteran

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    Exactly. Also, great catch Papa!
     
  16. Ande

    Ande Super Member ECF Veteran

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    "Safe chemistry" is a little like "safe sex," and using "protected batteries" is a little like "protected sex."

    There ARE inherent risks in all of the above, but if you observe basic safety precautions, all can be done without too severe a risk. (and all can be a pretty good time.)

    Maybe the term "safer chemistry" or "flameless venting" should be used. Cause "safe chemistry" might imply "risk-free chemistry" to the uninitiated, when it really only means "less risky." And even that is with some caveats.

    Best,
    Ande
     
  17. Ande

    Ande Super Member ECF Veteran

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    Damn internet. DOuble post.
     
  18. rolygate

    rolygate Forum Manager Admin Verified Member ECF Veteran

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    The main thing that we should be most concerned about is the possibility of a cell exploding in front of the face when vaping.

    Li-Mn cells (IMR's) are unlikely to do this. You could say 'impossible', but if we're talking safety then the term 'impossible' is best avoided...

    Protected Li-ion cells are also unlikely to do this. In theory it is more likely that a faulty protected Li-ion cell could explode than a faulty Li-Mn cell, but such incidents would be rare.

    So as far as use in e-cig mods is concerned, a Li-Mn cell is probably the best choice as it is the least likely to explode in the face. However, as they have a high C rating and no protection circuit, a large current can flow if shorted out (lots of amps). In fact there are models that can supply over 50 amps in this situation. So to say Li-Mn cells are 'safe' is wrong, there are no safe batteries of the type we use. More care needs to be taken with them than protected Li-ion cells because if shorted-out they are a miniature welding tool. You wouldn't want that happening in your pocket or purse, or at night in your house while asleep. So a mod that uses a Li-Mn cell (e.g. an AW 18650) must have a master on/off switch, and/or a fuse of some kind, plus gas vents, and/or it should have the end fitting (carto etc.) removed for transport/storage. You might say this should all be standard anyway, whatever the cell type (and since any kind of cell might be used in the mod, anyway).

    Any rechargeable mod battery with lithium in is potentially dangerous. The least attractive option though is one that can explode in your face, even if, as a consequence, that means it could burn up in your purse. Care has to be taken with all of them, you cannot treat a mod like an iPod.

    This is incorrect and the opposite of the facts. Maybe this was a typo.

    An IMR cell can supply many more amps than a Li-ion (Li-Co) whether protected or not. Perhaps the main feature of Li-Mn and some Li-FePo4 cells is the high current they can supply, one model can supply 70 amps in a dead short for example.

    If the Li-ion is protected and the protection is working correctly, it will not deliver more than the cutoff amperage, which is fairly low, before the thermal strip blows or other protection cuts in. Nevertheless, we consider a Li-Mn cell to be safer because there is much less likelihood of it exploding in the face, which is the most critical issue. It can suffer a catastrophic meltdown though, if abused (shorted out for example).

    There are no safe batteries of this type (that are generally available, suitable, and interchangeable with these cells for this duty - there are other, newer technologies that are not readily available, and there are safer batteries but they have different voltages).
     
  19. DarkAynjil

    DarkAynjil Senior Member ECF Veteran

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    The underlined is only true if your protection pcb functions correctly. I have had a Trustfire pcb short the battery it was supposed to protect, simply from dropping it into my box of vape gear before work. This led to thermal runaway, and I had to quickly drop the sucker into the bathtub. Later examination revealed horrible soldering from the factory was most likely to blame. I have also had an Ultrafire protected go into thermal runaway in a vv mod box. That one resulted in an interesting evening outside on my porch as I watched it spout a tiny jet of flame for a good two and a half minutes or so.

    Also, you'll find that if you're using smaller cells like 14500's that the regular protected cells will go into cutoff a lot, due to the fact that they can't push the current you need for say, a dct, or a lr carto or whatnot.


    IMO, you're better off and safer using IMR's in smaller-celled devices (14500's and such).
     
  20. Goldenkobold

    Goldenkobold Ultra Member ECF Veteran

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    I have never had a problem with an LR 1.5 306 stopping a 14500 from trustfire or AW. I don't use Dual Coils at anything under 5v (and therefore I rarely use dual coils as it means pulling out there own special rig).

    I don't think either battery is safe, it may not be the best motto for the promotion of mod usage but I have had protected batteries fail (an ego and a 14500). The ego came off the charger and started heating up, it got hot enough to smolder the paper it was sitting on and was too hot to touch, I moved it outside away from the house. The next day it was still in one piece. I am well aware that once that protection goes there is nothing between you and that unsafe chemistry.

    I spent 5 years working with aircraft safety and know that even with 4 or 5 layers of safety features there will always be that once incident where all of the safety features fail and someone risks getting hurt. It is just a matter of percentages, it is going to happen. Even if your mod has built in protection and your battery is safe (either by circuit board or chemistry) it can happen.

    With Li-ion or IMR you have the awesome choice of venting and explosion or potentially catching fire (and a fire can be worse than an explosion depending on what combustibles are around and if you catch it). I think a catastrophic battery failure can be...catastrophic...no matter which you choose.

    The safest choice isn't IMR or protected Li-ion but awareness of whichever you choose, I don't let my batteries charge past the green light on my charger (I am aware my charger is suppose to start cycling at that point and have its own protection but still...). I don't use batteries that have been dropped or show wear and tear around the circuit board (if your using a metal mechanical mod any wear and tear around the tape surrounding the body can also cause a short). I try not to leave my battery in the mod unattended or at the very least have the mod turned off. Some mods have built in protections...anything to lower your chances.

    The only safe choice is probably a puck using off the shelf batteries that don't recharge (I know ECF doesn't recommend it due to the chance of confusing your batteries and throwing them in a charger) but this is an amazingly costly way to vape. I don't know why a NiMh AA style puck isn't considered safer than a IMR battery and listed as the safest way to vape, All NiMh failures I have heard about came from charging (and generally from RC hobbyist charging in strange ways) and never from being carried or used.
     
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